bus: ti-sysc: Use PTR_ERR_OR_ZERO() to simplify code

Fixes coccicheck warning:

drivers/bus/ti-sysc.c:506:1-3: WARNING: PTR_ERR_OR_ZERO can be used
Reported-by: NHulk Robot <hulkci@huawei.com>
Signed-off-by: Nzhengbin <zhengbin13@huawei.com>
Signed-off-by: NTony Lindgren <tony@atomide.com>

drivers/bus/ti-sysc.c

@@ -503,10 +503,8 @@ static int sysc_init_resets(struct sysc *ddata)
 {
 	ddata->rsts =
 		devm_reset_control_get_optional_shared(ddata->dev, "rstctrl");
-	if (IS_ERR(ddata->rsts))
-		return PTR_ERR(ddata->rsts);
 
-	return 0;
+	return PTR_ERR_OR_ZERO(ddata->rsts);
 }
 
 /**